SESSION OF THE CORBILLERAN SECTION 493 



Session of the Cordilleran Skction, Friday, December 28 



The second annual meeting of the Cordilleran Section of the Society 

 was called to order at 10.30 a m, December 28, 1900, in the council-room 

 of the California Academy of Sciences, San Francisco. 



In the absence of the Chairman, Professor Joseph Le Conte, Mr W. P. 

 Blake* was elected temporary Chairman. 



The minutes of the last meeting were read and approved. 



The election of officers for the ensuing year was then taken up, with 

 the following result: 



W. C. Knight, Chairman ; A. C. Lawson, Secretary ; A. S. Eakle, 

 Councillor. 



These three officers are to serve as an Executive Committee for the 

 year. 



A committee consisting of Fellow^s Lawson, Branner, and Claypole was 

 appointed to formulate rules and regulations for the government of the 

 Section. 



The following papers were then read : 



EVIDENCES OF SHALLOW SEAS IN PALEOZOIC TIME IN SOUTHERN ARIZONA 



BY WILLIAM P. BLAKE 



[AbstracQ 



In the mountain ranges of southern Arizona there is abundant evidence of shal- 

 low seas and shorelines in Paleozoic time. These shores were not, perhaps, a 

 continental margin, ])ut rather the borders of islands, crests of submerged moun- 

 tain ranges rising at intervals above the Paleozoic ocean and with a trend or direc- 

 tion corresponding eventually to the direction of the mountain ranges of the 

 region. 



A cross-section of the territory northeasterly from the gulf of California shows 

 a succession of mountain ranges, some, fifteen in number, in most of which ancient 

 sandstones and contrlomerates of Paleozoic age have been identified. Many of the 

 exposures of quartzite are very thick, and these quartzites generally rest upon a 

 coarse-grained porphyritic granite. Deep-sea deposits are not wanting. Thick 

 beds of limestone, especially those of the Carboniferous, give evidence of depressed 

 areas and of oscillations of level. So also the existence of thick, uplifted beds of 

 graphitic coal in theChiricahua mountains bear testimony to the former existence 

 of land areas, and show a far western extension of the vegetation of the Carbon- 

 iferous. 



Two localities of Devonian beds were described— one in the Santa Ritas and 

 another at the northern end of the Santa Catalina mountains. 



The probable existence of Cambrian beds at several places was pointed out, and 

 the ancient tabular gneissic rocks of the Catalinas were referred to the Archean 

 and regarded as probable equivalents of the Huronian and Laurentian. 



* Mr Blake is an ex-Fellow of the Society. 

 LXX— Boll. Gkol. See. Am., Vol. 12, 1900 



